function generateUUID(){ 
    var d = new Date().getTime()
    if (window.performance && typeof window.performance.now === "function") { 
        d += performance.now()
    }
    var uuid = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) { 
        var r = (d + Math.random() * 16) % 16 | 0; d = Math.floor(d / 16) 
        return (c == 'x' ? r : (r & 0x3 | 0x8)).toString(16)
    })
    return uuid
}
console.log(generateUUID())